springBean生命周期解析
本文基于Spring5.3.7
参考：
kykangyuky Spring中bean的生命周期
阿斌Java之路 SpringBean的生命周期，
杨开振 JavaEE互联网轻量级框架整合开发
黑马程序员 JavaEE企业级应用开发教程
马士兵 Spring源码讲解
一. SpringBean生命周期流程图
二. 示例代码
1. 定义果汁描述实体类
package com.xiaobai.spring_bean_life_cycle;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
/**
* @author wangtw
* @date 2023/6/24 16:38
* @description 果汁描述实体类
*/
@Slf4j
@Data
public class Source {
public Source() {
log.info("source实例化");
}
/**
* 水果
*/
private String fruit;
/**
* 糖量
*/
private String sugar;
/**
* 大小
*/
private String size;
}
2. 定义果汁生成器
package com.xiaobai.spring_bean_life_cycle;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.*;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
/**
* @author wangtw
* @date 2023/6/24 16:28
* @description 果汁生成器
*/
@Slf4j
@Data
public class JuiceMaker implements BeanNameAware, BeanFactoryAware,
ApplicationContextAware, InitializingBean, DisposableBean {
public JuiceMaker(){
log.info("juice实例化");
}
private String beverageShop;
private Source source;
/**
* 自定义初始化方法
*/
public void init() {
log.info("【{}】执行自定义初始化方法", this.getClass().getSimpleName());
}
/**
* 自定义销毁方法
*/
public void myDestroy() {
log.info("【{}】执行自定义销毁方法", this.getClass().getSimpleName());
}
public String makeJuice() {
String juice = "这是一杯由" + beverageShop + "饮品店，提供的" + source.getSize() + source.getSugar() + source.getFruit();
return juice;
}
@Override
public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
log.info("【{}】调用BeanFactoryAware接口的setBeanFactory方法", this.getClass().getSimpleName());
}
@Override
public void setBeanName(String s) {
log.info("【{}】调用BeanNameAware接口的setBeanName方法", this.getClass().getSimpleName());
}
@Override
public void destroy() throws Exception {
log.info("调用接口DisposableBean的destroy方法");
}
@Override
public void afterPropertiesSet() throws Exception {
log.info("【{}】调用InitializingBean接口的afterPropertiesSet方法", this.getClass().getSimpleName());
}
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
log.info("【{}】调用ApplicationContextAware接口的setApplicationContext方法", this.getClass().getSimpleName());
}
}
3. 定义Bean实现BeanPostProcessor接口
package com.xiaobai.spring_bean_life_cycle;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;
/**
* @author wangtw
* @date 2023/6/24 16:07
* @description
*/
@Slf4j
public class BeanPostProcessorImpl implements BeanPostProcessor {
@Override
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
log.info("【{}】对象{}预初始化开始", bean.getClass().getSimpleName(), beanName);
return bean;
}
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
log.info("【{}】对象{}预初始化完成", bean.getClass().getSimpleName(), beanName);
return bean;
}
}
4. 定义SpringBean配置类
package com.xiaobai.spring_bean_life_cycle;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/**
* @author wangtw
* @date 2023/6/25 10:33
* @description Spring配置类
*/
@Configuration
public class LifeConfiguration {
@Bean("beanPostProcessor")
public BeanPostProcessor beanPostProcessor() {
return new BeanPostProcessorImpl();
}
@Bean("source")
public Source source() {
Source source = new Source();
source.setFruit("橙汁");
source.setSugar("少糖");
source.setSize("大杯");
return source;
}
@Bean(value = "juiceMaker", initMethod = "init", destroyMethod = "myDestroy")
public JuiceMaker juiceMaker() {
JuiceMaker juiceMaker = new JuiceMaker();
juiceMaker.setSource(source());
juiceMaker.setBeverageShop("贡茶");
return juiceMaker;
}
}
5. 测试类及输出结果
package com.xiaobai.spring_bean_life_cycle;
import lombok.extern.slf4j.Slf4j;
import org.junit.jupiter.api.Test;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
/**
* @author wangtw
* @date 2023/6/25 10:40
* @description springBean生命周期测试类
*/
@Slf4j
public class SpringBeanLifeTest {
@Test
public void testLifeCycle() {
ConfigurableApplicationContext context = new AnnotationConfigApplicationContext(LifeConfiguration.class);
JuiceMaker juiceMaker = (JuiceMaker) context.getBean("juiceMaker");
log.info(juiceMaker.makeJuice());
context.close();
}
}
三. 源码解析
（一）Bean实例化
1. 根据注解加载Bean
org.springframework.beans.factory.config.BeanFactoryPostProcessor
org.springframework.context.annotation.ConfigurationClassPostProcessor#processConfigBeanDefinitions
org.springframework.context.annotation.ConfigurationClassParser#parse(java.util.Set
org.springframework.context.annotation.ConfigurationClassParser#parse(org.springframework.core.type.AnnotationMetadata, java.lang.String)
org.springframework.context.annotation.ConfigurationClassParser#processConfigurationClass
org.springframework.context.annotation.ConfigurationClassParser#doProcessConfigurationClass
2. 在SpringBean实例化前会把扫描到的类加载到BeanDefinition中，然后将BeanDefinition中的信息注册到Spring容器中
org.springframework.context.annotation.AnnotationConfigApplicationContext#AnnotationConfigApplicationContext()
org.springframework.context.annotation.AnnotationConfigApplicationContext#register
org.springframework.context.annotation.AnnotatedBeanDefinitionReader#doRegisterBean
org.springframework.beans.factory.support.BeanDefinitionRegistry#registerBeanDefinition
3. 完成了BeanDefinition注册后，对Bean进行实例化
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#createBeanInstance
（二）初始化
1. 属性赋值
（1）自定义对象属性赋值
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#populateBean
（2）容器对象赋值：检查aware接口并设置相关依赖（aware接口用于标记，判断调用什么方法）
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#invokeAwareMethods
2. 执行前置处理方法
org.springframework.beans.factory.config.BeanPostProcessor#postProcessBeforeInitialization
3. 执行初始化方法
（1）检测Bean是否实现了InitializingBean接口
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#invokeInitMethods
（2）调用afterPropertiesSet方法
org.springframework.beans.factory.InitializingBean#afterPropertiesSet
（3）调用自定义初始化方法
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#invokeCustomInitMethod
4. 执行后置处理方法
org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#postProcessAfterInitialization
org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#wrapIfNecessary
创建代理对象
org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#createProxy
org.springframework.aop.framework.AopProxy#getProxy(java.lang.ClassLoader)